Although the present invention can be used in any electronic apparatus, for convenience of explanation, it is mainly explained with respect to a navigation system. A navigation system performs travel guidance for enabling a user to quickly reach the selected destination. Typically, the navigation system displays a map image while superimposing thereon a mark representing the current location and notifies the user which intersection to reach the destination.
FIGS. 1A-1H illustrate an example of overall procedure and screen display involved in the navigation system for route guidance to a destination. FIG. 1A is an example of locator map screen of the navigation system when a destination is not specified. Typically, the navigation system displays a street on which the vehicle (current vehicle position VP) is running, on a map image and a name of the street.
FIGS. 1B-1F illustrate an example of a process for specifying a destination in the navigation system. When selecting a “Destination” menu on a menu screen of FIG. 1B, the navigation system displays an “Find Destination By” screen as shown in FIG. 1C for specifying an input method for selecting destination.
When the user's finger touches, for example, an “Address” on the screen (touch panel) in FIG. 1C, the “Address” method is selected and the navigation system displays a keyboard screen as illustrated in FIG. 1D. Suppose the user has input an address “2525 W. Carson” of a shopping mall, the navigation system displays a “Confirmation Destination” screen shown in FIG. 1E.
If the name and address on the screen shows the correct destination, the user enters and “OK to Proceed” key to proceed the next procedure. The navigation system calculates and determines a quickest way to the destination address as illustrated in FIG. 1F. Then the navigation system starts the route guidance as illustrated in FIG. 1G. When the user approaches the destination within a determined distance, the navigation system indicates that the destination is ahead as illustrated in FIG. 1H.
In a current navigation system, as a user inputs a street name characters from the order of the first character to the end, the navigation system checks the matching street name candidates based on the characters which have been input so far, by retrieving the candidate street names from the database. The navigation system automatically moves to a new screen including address candidates, irrespective of the input velocity by the user, when the matching entries are listed to a certain number even though the user is about to input some other characters. In this case, the user cannot stop current input operation even though an unexpected new screen appears on the display screen, which results in an unsuccessful input operation.
Namely, the current navigation system automatically completes input and grays-out buttons to disable some keys of the keyboards while keeping enabled keys in a normal color without considering how quickly the user wants to input a set of characters, nor does the navigation system know if the user is about to supply additional input. For example, suppose a user, who does not know the exact street name, has only input the first several characters of the street and stopped inputting the street name to remember what to input next. In this case, the automatic-complete (auto-complete) function starts working irrespective of the intention of the user.
An auto-complete function is a search function where when inputting first few characters in an input field of the screen, the CPU of a navigation system extends the street name search by looking up all names that match the base name regardless of the of the other components of the street name, such as a prefix, thereby increasing the possibility of finding matching entries from the database.
Further, since the current navigation system does not understand the user's finger movement, there arises a case where the navigation system displays a pop-up screen which is not related to the input operation, just before user's input operation. For example, suppose the user sees and understands the current system state illustrated in FIG. 1C and is about to select the “Address” method. While the user's finger is approaching the input device, there is a case that the state of the navigation system has been changed due to the sudden event such as a warning message that requires another time critical attention, etc.
FIGS. 2A-2E illustrate the input operation of the navigation system associated with the forgoing problems. The user sees and understands a current system state through the screen on the navigation system as illustrated in FIG. 2A. Then the user moves the finger to the touch panel to interact with the information displayed on the screen. In this case, the user selects an inputting method of the “Address” as illustrated in FIG. 2B.
Suppose that just before touching the screen, a pop-up screen, unrelated to this input operation is displayed on the screen due to the system event requested from other tasks or operating system of the navigation system as shown in FIG. 2C. However, the user cannot stop inputting action because the time interval between the start of user's action and the appearance of the pop-up screen is too short to suspend this action as shown in FIG. 2D. As a result, the user touches the key even though the state of the navigation system has been changed and this input operation becomes invalid in the new system state.
FIG. 2E illustrates the input operations described above in a time sequential manner. In FIG. 2E, points A, B, C and D correspond to the states of FIGS. 2A-2D, respectively. The system state has not been changed between point A and just prior to point C where the pop-up screen has appeared on the screen at point C. Since the system has been changed from the point C to D, the input operation conducted between this period is no longer valid.
For the problems described above, Japanese Patent Application Laid-Open Publication No. H11-65769 discloses a display control method for enlarging the neighborhood of user's finger on the screen when the distance from the finger to the touch panel is within a predetermined range. Japanese Patent Application Laid-Open Publication No. 2000-122450 discloses an image forming apparatus having a function for providing necessary information related to the switch for the user by detecting the position of the user's finger before the finger contacts the touch panel. Further, U.S. Pat. No. 7,002,556 discloses a touch responsive display and method for determining the position of user's finger by using a sensor to provide necessary information to the user before contacting the touch panel.
According to these techniques, the existence of the user's finger is detected to control the navigation system. However, the navigation system always determines solely based on distance such that the user is about to input information when the user's finger is within a certain distance from the input device. Thus, a precise user's action has not been detected such as when the user's finger is about to remove from the certain distance from the input device. Therefore, there is a need of more precise way for detecting and tracing the movement of user's finger to correctly interact the information and system state of the navigation system.